1. Field of the Invention
The present invention relates to a honeycomb structure, made of cordierite, used for the catalyst support of an exhaust gas purification apparatus of an internal combustion engine, and to its production process.
2. Description of the Related Art
Hitherto, a honeycomb structure provided with a plurality of cells in which partitions made of cordierite and so forth were arranged in the form of honeycombs was used as a catalyst support of exhaust gas purification apparatuses. An exhaust gas purification function is demonstrated by loading an exhaust gas purification catalyst on the surfaces of the partitions of this honeycomb structure.
However, the above-mentioned honeycomb structure of the prior art has problems such as those indicated below.
Namely, accompanying the tightening of automobile exhaust gas controls in recent years, studies have been conducted for changing the mounting location of the catalyst support to a location closer to the engine than in the prior art for the purpose of more rapidly activating the catalyst of the exhaust gas purification apparatus. The object of this is to activate the catalyst more rapidly by raising the exhaust gas temperature that comes in contact with the catalyst to a higher temperature than in the prior art (by 50-100.degree. C. as compared with the prior art).
Although this increase in exhaust gas temperature accelerates catalyst activation, on the other hand, it also increases susceptibility of separation of the catalyst layer from the catalyst support. In addition, if separation of the catalyst layer occurs, it has a significant effect on the durability of the exhaust gas purification apparatus. Consequently, there has been a need to develop a honeycomb structure that is able to suppress separation of the catalyst layer even at high temperatures.
In consideration of the problems of the prior art as described above, the present invention provides a honeycomb structure that is able to suppress separation of the loaded catalyst layer much better than the prior art, and its production process.